Articulation system for articulated depressed-floor tramway carriages

ABSTRACT

The articulation system relates to articulated tramway carriages comprising at least two bodies, the opposing ends of which are connected together in an articulated manner in order to maintain substantial continuity of the walking surface, and are supported by wheels at or adjacent to the articulation zone. In the articulation system, the end of each body is supported on its own axle provided with independent wheels, the opposing bodies and the relative axles being connected together by means of a drawbar, slidable connections and/or connecting rods to jointly form a bogie with a non-rigid frame. The axle is of double swanneck shape with uprights for connecting disc brakes on the outside of the wheels.

TECHNICAL FIELD

This invention relates generally to articulated tramway carriages, andmore particularly to a system for connecting together twodepressed-floor carriages by means of an articulation system whichallows them to follow a curved path and allows the passengers to passthrough the articulated zone along a walking surface at the same levelas the depressed floor of the two carriages.

BACKGROUND OF THE INVENTION

The fact that the walking surface is at a low level facilitatespassenger entry and exit, thus reducing on the one hand passengerfatigue and on the other hand the halt time for their entry into thecarriage, with consequent reduction in the commercial speed.

Carriages comprising two bogies with a depressed floor in the zonebetween the two bogies have been constructed and are in service, but thedepressed floor part represents only a limited proportion of thecarriage floor lying between the parts which are raised above the twoend bogies.

Recently, in order to construct articulated tramcars with a depressedfloor in the zone between the two motorized end bogies, use has beenmade of articulated systems comprising a conventional bogie with verysmall wheels which is disposed in proximity to the articulatedconnection, or comprising a traditional bogie with idle wheels and avery low central thrust bearing.

The currently known articulation systems with a depressed floor havenumerous drawbacks, including the following.

The extent by which the carriage walking surface is lowered is not suchas to reach a level above the rail which allows entry to the carriagewithout the aid of at least one raisable or retractable step structure.The result is that the ease and speed of entry of the passengers is onlyslightly increased, and with it the commercial speed, due to thepresence of two step rises for entry purposes.

Care must be taken that the step structure does not emerge where raisedpavements are provided at stopping points.

Precautions must be taken against the passenger becoming caught in thestep structure so that it cannot be retracted or raised, with the dangerof it being able to drag the passenger along when the carriage moves.

The use of small-diameter wheels to obtain this lowering reduces safetyboth with regard to the wheel loading capacity and with regard toderailment due to the reduced guiding capacity of the wheel flange inreduced-pitch bogies.

The use of braking by means of discs when small-diameter wheels are usedis difficult because of the small diameters of the discs themselves,which have to satisfy the prescribed clearances from the rail level.

If the braking is by means of shoes acting on the wheel rolling face, itis practically impossible to use elasticized wheels with rubber insertsbecause of wheel heating on braking.

The difficulty experienced by handicapped persons in entering thecarriage.

SUMMARY OF THE INVENTION

The object of the present invention is to substantially improve themethod of construction, operation, maintenance and utilization withrespect to currently known systems, so obviating the aforesaid drawbacksby providing an articulation system for connecting together two or morebodies in such a manner as to maintain the walking surface at the samelevel even when passing over the articulated connection, to thusincrease the proportion of depressed floor of the assembly, and enablethe carriage walking surface to be lowered to a height above the raillevel such as to allow direct access to the carriage, thus eliminatingthe retractable or raisable step structure.

More particularly, the invention relates to an articulation system forarticulated depressed-floor tramway carriages with at least two bodies,the opposing ends of which are articulatedly connected together tomaintain substantial continuity of the waling surface and are supportedby wheels at or adjacent to the articulation zone, said system beingcharacterized in that the end of each body is supported on its own axleprovided with idle wheels, and in that the opposing bodies and therelative axles are connected together by means of a drawbar, slidableconnections and/or connecting rods to jointly form a bogie with anon-rigid frame.

Preferably, each axle has a configuration, when viewed in a verticalplane, which is substantially in the form of a double swan-neck with adepressed central zone provided with a seat for rotatably supporting therelative body.

Preferably, each axle supports a substantially semi-cylindricalstructure connected to the symmetrical structure supported by the otheraxle to form a turn-cage connection cover, substantially free ofdiscontinuity, between the two carriage bodies.

As a modification, each axle supports a bellows system to form aconnection cover with mobile platform footboards and provided with sideprotection panels in line with the side walls of the carriages in orderto protect up to a certain height those members of the unconventionalbogie which are exposed, for safety reasons.

Inasmuch as this invention is applicable both to tramway cars(streetcars and metro cars) and to railroad vehicles, it should beunderstood that "railway carriages" as used herein, is generic to allsuch vehicles.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is hereinafter further clarified, with referenceto the accompanying drawings.

FIG. 1 is a diagrammatic elevational view of an articulated carriageformed from three bodies provided with the connection and articulationsystem according to the present invention;

FIG. 2 is an analogous illustration to that of FIG. 1, but in plan view;

FIG. 3 is a diagrammatic plan view of the connection and articulationzone of two opposing carriages, showing a so-called turncage connection;

FIG. 4 is an illustration analogous to FIG. 3, but showing a bellowsconnection;

FIG. 5 is a partly sectional plan view, taken transversely to thecarriage, showing the axle with idle wheels;

FIG. 6 is a vertical section through the axle on the line VI--VI of FIG.5;

FIG. 7 is a side elevation of the axle of FIG. 5; and

FIG. 8 is a side elevation on the line VIII--VIII of

FIG. 5, showing the telescopic tube in section.

BEST MODE OF CARRYING OUT THE INVENTION

With reference to the drawings in detail, FIGS. 1 and 2 show adiagrammatic example of an articulated carriage comprising three bodies1, 2 and 3, each provided with a depressed floor 4, forming a constantlevel which is raised only at 5 in positions corresponding with the twoend bogies 6 which are located below the bodies 1 and 3. In a positioncorresponding with each articulation system between the bodies 1 and 3and the central body 2, there are disposed the central bogies 7 formedfrom two axles connected together in such a manner as to constitute anon-rigid unconventional bogie with idle wheels, according to theinvention. The ends of the bodies 1, 2 and 3 rest on these axles. Thesystem is completed by two semi-cylindrical portals 8 connected togetherby the articulated footboards 9 to provide floor continuity, and by theelastic wall 10 (these being shown in the connection zone between thebody 1 and body 2), or is alternatively completed, as a modification, bytwo body end walls 11 connected to the bellows interconnection piece 12,turntable footboards 13 and mobile platform footboards 9 with sideprotection panels of bellows type 15 or telescopic type 16 hinged to theends of the side walls, which protection panels can be limited in heightto the extent necessary for protecting the public from the exposed bogieparts.

The articulation and mechanical connection system between two bodiesindicated by 7 in FIGS. 1 and 2 is more apparent from an examination ofFIGS. 5, 6, 7 and 8.

The reference numeral 20 indicates an axle according to the invention inthe shape of a double swan-neck, from the ends of which there projectjournals 21 which support the wheels 22, and each of which carries, onthe outside of the wheels, a disc 23 for the wheel disc-braking systemFR, comprising a brake cylinder CF. Each wheel 22 is mounted, rigidlytogether with its disc, on the journal 21 by means of bearings in orderto rotate independently from the other wheel of the axle. From each ofthe two ends of the axle 20 there also extends an upright 24 forcarrying the projecting support arm 25 for the lever system 26 whichoperates the brake pads of the discs 23.

At the depressed center of the axle 20 there is disposed a seat 27 whichinternally carries a lower ring 28 of a preferably pneumatic suspension29, the ring being supported on the axle by a ball bearing 30 to allowthe suspension to rotate about the seat 27. Upperly, and rigid with it,the suspension 29 carries a ring 31 on which the body structure 34 restsby way of a support ring 35 made rigid with the body by means of thebrackets 33. The suspension 29 carries the normal end-of-travel buffers32. In the support ring 35 there is housed a bearing 36 with both axialand radial bearing capacity and supporting the lower central pivot 37 ofthat half of the articulation turntable 38 relative to one of thebodies.

The bodies are connected together by a drawbar 40 pivoted at 41 on thesupport ring 35. The drawbar 40 is connected by one of its rigid pins 42to the connecting rods 43 which transmit to the bodies the longitudinalforces due to the motion and braking resistance. The axles 20 areconnected together by a telescopic cylindrical connection 44 rigid withthe axles 20 by way of the structures 45 and 46, which are themselvesrigid with the axle seat 27.

The longitudinal connection of the axle is completed by the pins 47rigid with the structures 45 and 46 and connected to the second end ofthe connecting rods 43. The telescopic connection thus ensuresparallelism of the axles, prevents the axles rotating about the wheelaxis, allows the axles to make skew movements, and allows the making ofthe longitudinal movements required by the movements of the drawbar 40or of the connecting rods 43.

The body support ring 35 comprises a counteracting shoe 39 cooperatingwith a relative buffer 48 rigid with the axle 20 in order to limit therelative oscillations made by each axle in directions parallel to thewheel axis beyond the elastic limits allowed by the transverseelasticity of the suspension 29.

A torsion bar 50 connected by the arms 51 and connecting rods 52 to theaxle 20 can be provided for aiding stabilization of the bodies, inparticular of the intermediate body which rests on two points.

The torsion bar, disposed close to the body, reacts against the bodysupport brackets 33 by way of the supports 53.

Floor continuity is provided by the turntable platform 38 rigid with thepivot 37 and by the articulated footboards 9, it therefore beingapparent from the aforegoing description that the tramway carriageconstructed with the axle according to the invention, comprising idlewheels, enables the floor to be depressed continuously to the samelevel, including at the articulation systems between the bodies, withthe exception of the positions corresponding with the end bogies. Theadvantages obtained are as follows:

substantial increase in the ease and speed of passenger entry, withdefinite reduction in the halt time to the advantage of the commercialspeed;

simplification of the carriage construction by eliminating theretractable or raisable step mechanism:

simplification of the car operating system by eliminating the automaticdevices necessary for governing the step movements when raised pavementsare present at stopping points;

increase in operating safety, as no special arrangements are necessaryfor protection against misure of the step structure by passengers;

facility for easy entry of handicapped persons in wheelchairs.

The system has no limitations with regard to wheel diameter, withsubstantial advantages in terms of wheel loading capacity and wear andin terms of the guiding function required of the wheel flange.

The system can use wheels of the same diameter as the wheels ofconventional bogies, which simplifies maintenance as the wheels can betired and provided with an elasticized part with rubber types andinserts which are equal for the entire carriage.

The system allows disc brakes to be mounted without diameter limitation,thus providing maximum reliability in braking.

The use of disc brakes enables the wheels to be elasticized as they donot become heated, there being no need for the action of friction by thebrake shoes on the tyres for braking purposes.

The use of independently wheeled double swan-neck axles connectedtogether to form an unconventional bogie enables the carriagearticulation system to undergo good curving, and allows passengers topass through the articulated zones along a walking surface at the samelevel as the depressed floor of the articulated carriage.

I claim:
 1. In a suspension system for a pair of articulateddepressed-floor railway carriages, of the type wherein adjacent car endsare pivotally interconnected by means of a drawbar, each of said ends issupported by a single-axle bogie, and each of said bogie comprises adropped-center axle and a pair of wheels mounted for free independentrotation thereon, the improvement comprrising(a) a single resilientsuspension element interposed between said car body and said axle at thecenter thereof, (b) means for permitting the axle to pivot about avertical axis relative to said car body, and (c) a constraint forpreventing rotation of said axle around the rotational axis of saidwheels.
 2. The invention of claim 1 wherein the axle has a depressedcentral zone and further comprises a seat centrally located within saidzone for supporting said suspension and pivoting means.
 3. The inventionof claim 1 wherein the means for permitting the axle to pivot is athrust bearing interposed between the car body and the axle at thecenter thereof.
 4. The invention of claim 1 wherein said means centralresilient suspension element is capable of yielding torsionally and themeans permitting the axle to pivot is the suspension element itself. 5.The invention of claim 1 wherein the suspension is pneumatic.
 6. Theinvention of claim 5 further comprising means for transmittinglongitudinal forces between the axle and its respective car body.
 7. Theinvention of claim 6 wherein said force transmitting means comprises aconnecting rod pivotally connected at one end to the axle and pivotallyconnected at the other end to the car body.
 8. The invention of claim 1wherein said constraint comprises a pair of tubular telescopinglongitudinal elements each directly connected to a respective one ofsaid axles.
 9. The invention of claim 1 further comprising a shoe and aseat in proximity to the shoe for contacting the same to preventexcessive lateral movement of the axle with respect to the car body, theshoe and seat being disposed respectively one on the axle and one on thecar body.
 10. The invention of claim 1 further comprising a brake discmounted to each of said idler wheels.
 11. The invention of claim 10further comprising braking means for engaging said brake disc, saidbraking means being supported from the axle.
 12. The invention of claim1 further comprising an anti-sway torsion bar for at least one of saidaxles.
 13. The invention of claim 1 wherein each axle supports asemi-cylindrical structure connected to a like structure of the otheraxle to form a turn-cage connection cover substantially free ofdiscontinuity between the two car bodies.
 14. The invention of claim 1further comprising a bellows connection forming a connection cover withmobile platform foot boards and having side protection panels in linewith side walls of the car body to shield exposed portions of the bogie.